Upvote a comment on behalf of the authenticated user
upvotes array. Removes the user from downvotes if previously downvoted. Increases the reputation of the comment author and sends a notification.
Missing Comment ID - 400 Bad Request
Not Found - 404 Not Found
Already Upvoted - 409 Conflict
Server Error - 500 Internal Server Error
409 Conflict error is returned.downvotes if previously present.